(loosely) A contradiction in terms. Historically, an oxymoron was a paradox with a point, where the contradiction seems absurd at first glance, and yet is deliberate, its purpose being to underscore a point or to draw attention to a concealed point.
By far the most massive planet in our solar system, Jupiter features giant hurricanes, auroras, abstract artistic cloudswirls, and maybe even a solid core. It also protects Earth by gravitationally clearing the solar system of asteroids and comets.
If we kept descending, we likely would eventually come to a solid core. But the interior pressure on Jupiter is millions of times greater than on the Earth. The heat and pressure would have destroyed us and our spacecraft long before we got to that core.